1. Field of the Invention
This invention relates to an image forming apparatus, such as a copier, a printer, a plotter, a multifunction machine including functions of those, and in particular to an electro-photographic image forming apparatus capable of forming a toner image on a photoconductive member by charging, writing, developing, transferring the toner image either directly or indirectly via an intermediate transfer member using a transfer device, on a transfer medium, such as a sheet, etc., and fixing the toner image using a fixing device.
2. Discussion of the Background Art
The image forming apparatus generally records an image including character and symbol or the like on a transfer medium, such as a sheet, a cloth, an overhead projector film, etc., based on image information. Among various image forming systems, an electro-photographic image forming apparatus widely spreads due to high-speed and fine image printing on a plain paper.
In such an electro-photographic image forming apparatus, a charging device, a writing device, a developing device, a transferring device, a cleaning device, and a charge removing device are arranged around a drum shape belt type photoconductive member. When the surface of the photoconductive member is uniformly charged as the photoconductive member rotates, a writing process is executed and a latent image is formed thereon. Then, a toner image is formed by adding toner and developing the latent image. The toner image is then either directly or indirectly transferred via an intermediate transfer member, such as a belt, etc., on a transfer medium.
The transfer medium is lead to the fixing device after the toner image transfer process, and an unfixed toner image is fixed onto the transfer medium. The surface of the photoconductive member is cleaned by a cleaning device after the image transfer process, while charge remaining thereon is removed, thereby the next image formation becomes standby.
In this type of electro-photographic image forming apparatus, an optional relation between the transfer device and the fixing device is very important, because the relation largely affects conveyance quality, such as transfer medium curls, winkle, etc., and image quality, such as precision of color superimposition of toner images.
Then, the transfer device and the fixing device are conventionally supported by an image forming apparatus body, so that precision of attachment of these devices can be maintained with reference to the body, and a parallel degree between those devices can be adjusted during a manufacturing process while size precision is severely checked.
However, even if the parallel degree is strictly adjusted, curls or winkle occurs depending on various usage conditions at a user site or a toner image creates color deviation or the other problem. Further, as a cost of an image forming apparatus is decreasingly recently, adjustment of the parallel degree and strict adjustment of the size precision of those devices results in cost increase.